Near Field Communication (NFC) is a high-frequency wireless communication method applied in devices that are spaced from each other within about a distance of 10 cm. The NFC technology is an extension of the ISO/IEC 14443 proximity-card standard (Radio-Frequency Identification (RFID), contactless card) that combines the interface of an integrated circuit card (smartcard) and a reader into a single device.
Specifically, NFC communication occurs between two NFC compatible devices, and particularly between an initiator device and a target device. The initiator device chooses the bit rate of data transmission and initializes the communication with the target device.
Furthermore, NFC technology can operate in an active or a passive communication mode discussed below and all NFC devices are assumed to support both communication modes.
Analytically, in a so-called passive mode, an initiator device provides a carrier field and a target device answers by modulating this field. In the passive mode, the target draws operating power from the initiator's electromagnetic field and the target device's receiver is only required to acknowledge its presence when polled.
On the other hand, in an active mode, both the initiator device and the target device communicate by generating their own field. In this mode, both devices typically need a power supply.
In order to establish the above mentioned NFC communication between an initiator and a target device which are both NFC compatible, a device detection polling loop is applied. The device detection polling loop can be used by an initiator device to detect a target device or it can be used by a target device for being detected by an external initiator device.
More particularly, during the device detection polling loop, a periodic scanning detection process is performed. The periodic scanning detection, detects different data formats of an external device that can be either an initiator device or a target device.
Nowadays, the trend in wireless connectivity market is to integrate several connectivity cores in single chips. Specifically, in 3G generation, Global Positioning System (GPS), Bluetooth (BT) and FM cores are integrated in only one chip. Nevertheless, next generation chips are expected to additionally integrate the NFC connectivity core.
However, the above mentioned NFC core integration provokes significant impairments in the quality of NFC communication because of the close proximity of the NFC core and the FM core into the chip.
The close proximity of the two above mentioned cores results to interfering effects between the harmonics of the NFC core operation frequency (13.56 MHz) and the frequency of the FM broadcast band, when the FM core is tuned to a channel or frequency (hereinafter designed as the FM operation frequency) which is an harmonic of the NFC frequency. Specifically, the highest impact on the interference comes from the permanent function of the device detection polling loop operating in the NFC frequency.
Thus there is a need to improve the NFC communication between NFC compatible devices and decrease the interference effect resulting from the integration of an FM core and an NFC core in a single chip, which interference particularly arises when a tuned FM core frequency matches a harmonic of the NFC core operation frequency.